<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>JavaScript</title>
    <style>
        div{
            font-size: 50;
            color: orange;
        }
    </style>
</head>
<body>
    <div>
    <script>
            document.write("<h1>Hello world!</h1>");
    </script>
    </div>
</body>
</html>